1. Field of the Invention
The present invention relates generally to sound attenuation. More specifically, the present invention comprises an exhaust baffle which may be selectively placed in an exhaust pipe to reduce emitted exhaust sounds when desired.
2. Description of the Related Art
The present invention is particularly suited for use in motorcycle exhausts, and the embodiments disclosed in detail will use motorcycle exhausts as the example. However, the reader should bear in mind that the invention is by no means limited to this application and may be more broadly applied to any scenario in which noise reduction or an increase in back flow pressure is desired.
Motorcycles traditionally have fairly simple exhaust systems. This is particularly true for “V-Twin” engines such as those produced by HARLEY-DAVIDSON. Such exhausts typically provide fairly low sound attenuation. The result is a loud and “thunderous” exhaust tone that many motorcycle enthusiasts find desirable. The loud exhaust noise is in fact a signature effect of this type of motorcycle.
Unfortunately for those desiring the traditional exhaust sound effects, many municipalities have passed noise ordinances defining a maximum sound level permitted for operation of a moving vehicle. Many motorcycles exceed this sound level and may therefore not be legally operated within the particular municipality. The ordinances are not uniform, however. Thus, a motorcycle may be legally operated in many areas yet prohibited from a few areas which have enacted more strict noise ordinances.
One solution is of course to add a muffling device to reduce the exhaust noise so that it complies with the most restrictive noise ordinance. This would require significant sound attenuation. Most motorcycle owners would prefer to have the loud sound available wherever it is legal, and apply the reduced sound only when required. One can of course change exhaust systems, but this is cumbersome. One can also equip the exhaust with complex dual pathways selected by a butterfly valve (as is done in some automotive applications). Such mechanisms add to the weight and complexity of a motorcycle, and additionally tend to spoil the “clean” appearance most motorcycle enthusiasts desire. Thus, it would be preferable to provide a noise attenuating device which could be selectively added to an existing exhaust system without requiring significant modifications. The present invention proposes just such a design.